Module 2: Figure PLC structure and function
The domain structure and activation mechanisms of PLC isoforms.
The pleckstrin homology (PH) domain, four EF-hand domains, the catalytic X and Y domains, and the C2 domain are a common feature of most of the PLC isoforms. The two PLCγ isoforms differ from the others by lacking a C2 domain and by having additional domains such as the Src homology 2 (SH2) and Src homology 3 (SH3) domains located between a split PH domain. The black triangles indicate the sites of tyrosine phosphorylation that are important for the activation of PLCγ. PLCε also has additional domains related to its activation by Ras, such as the Ras association motifs (RA) and the Ras guanine nucleotide exchange factor (RasGEF). The bottom panel illustrates how the various PLC isoforms are activated by different mechanisms. Not included in this figure is the action of PLCζ, which is unusual in that it is activated at fertilization following its injection into the oocyte (Module 8: Figure mammalian fertilization).